Apparatus for the preparation of screen printing forms with an adjustable relation between grey values of the pattern and grey values of the printing forms

ABSTRACT

The instantaneous analog output of a scanning device is converted to one of a plurality of digital signals each of which corresponds to a different level of the analog signal. The output of the scanning device is a function of the local intensity of a pattern and the digital signals appear at a plurality of individual output terminals. An engraving device includes a plurality of input terminals which control its cutting movement, and these input terminals are connected to the digital output terminals at a two-coordinate pin board so that the contrast of a pattern being scanned may be altered at will at the printing form being engraved.

United States Patent 91 de Vos et al.

[451 Apr. 24,1973

[54] APPARATUS FOR THE PREPARATION OF SCREEN PRINTING FORMS WITH AN ADJUSTABLE RELATION BETWEEN GREY VALUES OF THE PATTERN AND GREY VALUES OF THE PRINTING FORMS [75] Inventors: Ferdinand A. de Vos, Amsterdam; Jan H. ter Steege, Abcoude, both of Netherlands V [73] Assignee: Werkspoor-Amsterdam N.V., Am-

sterdam, Netherlands [22] Filed: Ap. 20, 1971 21 Appl.No.: 135,732

[30] Foreign Application Priority Data Dec. 1, 1967 Netherlands ..67l6368 Related US. Application Data [63] Continuation of Ser. No. 776,320, Nov. 18, I968,

ANALOG 7'0 DIGITAL CONVERTER TWO Coven/NA T [56] References Cited UNITED STATES PATENTS 3,027,548 3/1962 Vaughan ..340/i74 SP Primary Examiner-J. Russell Goudeau Att0rneySnyder & Butrum 57] ABSTRACT The instantaneous analog output of a scanning device is converted to one of a plurality of digital signals each of which corresponds to a different level of the analog signal. The output of the scanning device is a function of the local intensity of a pattern and the digital signals appear at a plurality of individual output terminals. An engraving device includes a plurality of input terminals which control its cutting movement, and these input terminals are connected to the digital output terminals at a two-coordinate pin board so that the contrast of a pattern being scanned may be altered at will at the printing form being engraved.

8 Claims, 1 Drawing Figure Patenfed April 24, 1973 -3-,7 29,584

ATTORNEYS APPARATUS FOR THE PREPARATION OF SCREEN PRINTING FORMS WITH AN ADJUSTABLE RELATION BETWEEN GREY VALUES OF THE PATTERN AND GREY VALUES OF THE PRINTING FORMS CROSS REFERENCE TO RELATED APPLICATION This application is a continuation of application, Ser. No. 776,320, filed Nov. 18, 1968 and now abandoned.

The invention relates to a method for preparing screen printing formes to a given pattern by means of an electro-magnetically controlled engraving member; I

In this known method the signals obtained by the scanning of the pattern are fed in a fixed ratio 'to the individual circuits making up the control circuit for the engraving member. This is a disadvantage, since the result is that the same contrast agreeing with the pattern is always obtained on the printing forme, so that motifs have different contrast when printed on different materials. The same printing forme produces a different contrast on, for instance, paper than on, for instance, linen. It is therefore desirable, in dependance on the material for which the printing forme is to be used, to make a predetermined photo-electrically scanned discrete color value of the pattern, the socalled grey value, correspond to a particular cutting movement of the engraving member, independently of the relation between the other measured grey values and the cutting movement.

.Another disadvantage of the fixed pattern between the measured grey value and the cutting movement of the engraving member is that there is no possibility of variation in contrast within a motif, such as is considered desirable in practice.

The invention achieves the afore-mentioned aims by the fact, that for the actuation of the engraving member, each of the discrete signals delivered by the converter circuit can be fed to each of the circuits controlling the engraving member.

This adjustability means that the method can be used to achieve any required contrast; to suppress measured grey values of the motif; or to combine a number of grey values for one resulting cutting movement of the engraving member.

An embodiment of the invention will now be described in greater detail with reference to the accompanying drawing, which is a block diagram of an apparatus for the performance of the method.

A printing form clamped on a cylinder 1 is processed by an engraving member 2 controlled by a circuit 3. The control signals for the circuit 3 are delivered by an analog-digital converter 4 which converts the analog signal delivered by a photo-electric scanning member 5 into a number of discrete values distributed over the whole range from white to black. The scanning member 5 scans a pattern disposed on a cylinder 6. The control circuit 3 consists of a number of individual circuits, the amplification of one circuit resulting in a predetermined corresponding cutting movement of the engraving member 2. The total number of possible cutting movements of the engraving member covers the whole range from white to black.

By connecting a two-coordinate pin board 7 between the control circuit 3 and the converter 4, each output of the converter 4, only one of which is amplified at every instant, can be connected to an input of the circuit 3, so that a required cutting movement of the engraving member can be made to correspond to a predetermined grey value at choice.

Alternatively, a number of outputs of the converter 4 can be connected to one input of the circuit 3, or certain outputs need not be connected. The user of the apparatus has therefore complete freedom on the basis of his own experience to select the programme which he requires for a particular pattern and/or a particular material to be printed.

It will be appreciatedthat the converter 4 produces an output signal at only one of its output conductors for each level of local intensity scanned on the original pattern. The two coordinate pin board 7 is simply a connector board by means of which any input conductor for the control circuit 3 may be connected to any one, or more, of the output conductors of the converter 4. By way of specific example as shown in the drawing, both the 2nd and nth output conductors of the converter 4 are connected to the 2nd input conductor of the control circuit 3, and the 1st output conductor of the converter is connected to the nth input conductor of the control circuit. It will be understood, of course, that other connections would also be made, but not all of the input conductors of the control circuit 3 would necessarily be connected to any output conductor of the converter 4. Whatever connections are made, the main objective is to be able to so connect the output and input conductors so that any desired program may be achieved which will allow the engraved pattern to display a variation of contrast within its motif which may be independent of and specifically different from the variation in contrast within the motif of the original pattern being scanned.

The analog-to-digital converter 4 may take any conventional form as for example as is described in the Koll et al. U.S. Pat. No. 3,272,918 and advantageously may be so constructed as to provide 32 discrete brightness steps between the darkest black and the brightest white as is described as conventional in the aforesaid Koll patent. Thus the conductors 1, 2, 3 n in the drawing leading from the converter 4 correspond to the conductors 6 in FIG. 1 of the K01] et al patent. The digital-analog converting mechanism 3 of the present invention may also take any conventional form as is also disclosed by the aforesaid Koll et al patent. And, thus, the conductors 1, 2, 3 n leading to the circuitry 3 in the present drawing correspond to the conductors in FIG. 1 of the K01] et al. patent.

What is Claimed is:

1. Apparatus for preparing screen printing forms comprising, in combination,

scanning means for progressively scanning an original pattern which displays a specific variation in contrast within its motif and said scanning means having a plurality of output terminals individually and selectively energized according to the localized intensity of the original pattern,

engraving means having a plurality of individually and selectively energized input terminals for producing a final pattern of varying local intensity on a screen printing form,

and control means selectively connecting said output terminals of the scanning means to said input terminals of the engraving means for controlling the local intensity of the final pattern produced by said engraving means independently of the local intensity of the corresponding portion of said original pattern to produce a final pattern which may display a variation in contrast specifically different from and independent of said specific variation in contrast of said original pattern.

2. Theapparatus as defined in claim 1 wherein said control means comprises a two-coordinate pin board.

3.Apparatus for preparing screen printing forms which may be used to print upon different materials on which the contrast of the printed pattern may vary in accord with the particular material, comprising, in combination;

scanning means for progressively scanning an original pattern and producing an analog signal whose amplitude varies in accord with the contrast in said original pattern; converter means connected to the output of said scanning means for converting said analog signal into discrete signals representative of the instantaneous amplitudes of said analog signal, said converter means having a plurality of output terminals at which said discrete signals uniquely and individually appear; circuit means having a plurality of input terminals equal to the number of said output terminals and adapted to be connected thereto for producing engraver-actuating output signals of different amplitudes dependent upon which of the input terminals is energized; engraving means connected to the output of said circuit means for engraving a pattern having a contrast controlled by the amplitudes of the engraveractuating signals; and means for selectively connecting said output terminals to said input terminals in any combination thereof whereby the user has complete freedom on the basis of his own experience to select the program which he requires for a particular engraved pattern. 4. Apparatus for preparing screen printing forms as defined in claim 3 wherein the last means comprises a two-coordinate pin board.

5. Apparatus for preparing screen printing forms comprising, in combination,

scanning means for progressively scanning an original pattern which displays a specific variation in contrast within its motif and said scanning means having a plurality of output terminals individually and selectively energized according to the localized intensity of the original pattern,

engraving means having a plurality of individually and selectively energized input terminals for producing a final pattern of varying local intensity on a screen printing form,

and control means selectively connecting said output terminals of the scanning means to said input terminals of the eqgraving means for controlling the local intensity 0 he final pattern produced by said engraving means independently of the'local intensity of the corresponding portion of said original 7 pattern to produce a final pattern which may display a variation in contrast specifically different from and independent of said specific variation in contrast of said original pattern.

6. Apparatus according to claim 5 wherein said scanning means comprises a photosensitive device having an analog output signal whose amplitude is proportional to the localized intensity of the original pattern, and an analog-to-digital converter having said plurality of output terminals, discrete ones of which are energized according to the amplitude of said analog output signal.

7. Apparatus according to claim 6 wherein said control means consists of connector means for connecting said output terminals of the converter to said input terminals according to any selected program.

8. The apparatus as defined in claim 7 wherein said connector means comprises a two-coordinate pin board. 

1. Apparatus for preparing screen printing forms comprising, in combination, scanning means for progressively scanning an original pattern which displays a specific variation in contrast within its motif and said scanning means having a plurality of output terminals individually and selectively energized according to the localized intensity of the original pattern, engraving means having a plurality of individually and selectively energized input terminals for producing a final pattern of varying local intensity on a screen printing form, and control means selectively connecting said output terminals of the scanning means to said input terminals of the engraving means for controlling the local intensity of the final pattern produced by said engraving means independently of the local intensity of the corresponding portion of said original pattern to produce a final pattern which may display a variation in contrast specifically different from and independent of said specific variation in contrast of said original pattern.
 2. The apparatus as defined in claim 1 wherein said control means comprises a two-coordinate pin board.
 3. Apparatus for preparing screen printing forms which may be used to print upon different materials on which the contrast of the printed pattern may vary in accord with the particular material, comprising, in combination; scanning means for progressively scanning an original pattern and producing an analog signal whose amplitude varies in accord with the contrast in said original pattern; converter means connected to the output of said scanning means for converting said analog signal into discrete signals representative of the instantaneous amplitudes of said analog signal, said converter means having a plurality of output terminals at which said discrete signals uniquely and individually appear; circuit means having a plurality of input terminals equal to the number of said output terminals and adapted to be connected thereto for producing engraver-actuating output signals of different amplitudes dependent upon which of the input terminals is energized; engraving means connected to the output of said circuit means for engraving a pattern having a contrast controlled by the amplitudes of the engraver-actuating signals; and means for selectively connecting said output terminals to said input terminals in any combination thereof whereby the user has complete freedom on the basis of his own experience to select the program which he requires for a particular engraved pattern.
 4. Apparatus for preparing screen printing forms as defined in claim 3 wherein the last means comprises a two-coordinate pin board.
 5. Apparatus for preparing screen printing forms comprising, in combination, scanning means for progressively scanning an original pattern which displays a specific variation in contrast within its motif and said scanning means having a plurality of output terminals individually and selectively energized according to the localized intensity of the original pattern, engraving means having a plurality of individually and selectively energized input terminals for producing a final pattern of varying local intensity on a screen printing form, and control means selectively connecting said output terminals of the scanning means to said input terminals of the engraving means for controlling the local intensity of the final pattern produced by said engraving means independently of the local intensity of the corresponding portion of said original pattern to produce a final pattern which may display a variation in contrast specifically different from and independent of said specific variation in contrast of said original pattern.
 6. Apparatus according to claim 5 wherein said scanning means comprises a photosensitive device having an analog output signal whose amplitude is proportional to the localized intensity of the original pattern, and an analog-to-digital converter having said plurality of output terminals, discrete ones of which are energized according to the amplitude of said analog output signal.
 7. Apparatus according to claim 6 wherein said control means consists of connector means for connecting said output terminals of the converter to said input terminals according to any selected program.
 8. The apparatus as defined in claim 7 wherein said connector means comprises a two-coordinate pin board. 